我是新面孔的3.2。我需要从SelectOneMenu的数据库中获取部门的所有名称，但我没有！
<h:outputText value="Département : " />
<h:selectOneMenu value="#{departementBean.departement}" converter="#{departementConverter}">
<f:selectItem itemLabel="Select One" itemValue="" noSelectionOption="true"/>
<f:selectItems var="dep" value="#{departementBean.list}" itemLabel="libelleDepartement" itemValue="#{departementBean.departement}" />
</h:selectOneMenu>
这是来自此Tuto How to populate options of h:selectOneMenu from database?
的DepartementConverter@ManagedBean(name = "departementConverter")
@RequestScoped
public class DepartementConverter implements Converter {
@ManagedProperty(value = "#{departementService}")
private DepartementService departementService;
@Override
public Object getAsObject(FacesContext context, UIComponent component, String value) {
Long id = Long.valueOf(value);
try {
return departementService.find(String.valueOf(id));
} catch (Exception e) {
throw new ConverterException(new FacesMessage(String.format("Cannot convert %s to Departement", value)), e);
}
}
@Override
public String getAsString(FacesContext context, UIComponent component, Object value) {
Departement departement = (Departement) value;
return String.valueOf(departement.getIdDepartement());
}
public DepartementService getDepartementService() {
return departementService;
}
public void setDepartementService(DepartementService departementService) {
this.departementService = departementService;
}
}
来自DAOImpl的查找方法如下：
public Object find(String id) {
return this.getHibernateTemplate().find(id);
}
但是当我运行项目时，我有这个错误：
INFO: Exception when handling error trying to reset the response.
java.lang.ClassCastException: java.lang.String
at com.majustic.majemploi.converter.DepartementConverter.getAsString(DepartementConverter.java:43)
at com.sun.faces.renderkit.html_basic.HtmlBasicRenderer.getFormattedValue(HtmlBasicRenderer.java:519)
at com.sun.faces.renderkit.html_basic.MenuRenderer.renderOption(MenuRenderer.java:534)
at com.sun.faces.renderkit.html_basic.MenuRenderer.renderOptions(MenuRenderer.java:792)
at com.sun.faces.renderkit.html_basic.MenuRenderer.renderSelect(MenuRenderer.java:844)
at com.sun.faces.renderkit.html_basic.MenuRenderer.encodeEnd(MenuRenderer.java:298)
at javax.faces.component.UIComponentBase.encodeEnd(UIComponentBase.java:875)
at com.sun.faces.renderkit.html_basic.HtmlBasicRenderer.encodeRecursive(HtmlBasicRenderer.java:312)
at com.sun.faces.renderkit.html_basic.GridRenderer.renderRow(GridRenderer.java:185)
at com.sun.faces.renderkit.html_basic.GridRenderer.encodeChildren(GridRenderer.java:129)
at javax.faces.component.UIComponentBase.encodeChildren(UIComponentBase.java:845)
at org.primefaces.renderkit.CoreRenderer.renderChild(CoreRenderer.java:57)
at org.primefaces.renderkit.CoreRenderer.renderChildren(CoreRenderer.java:45)
at org.primefaces.component.panel.PanelRenderer.encodeContent(PanelRenderer.java:185)
at org.primefaces.component.panel.PanelRenderer.encodeMarkup(PanelRenderer.java:108)
at org.primefaces.component.panel.PanelRenderer.encodeEnd(PanelRenderer.java:55)
at javax.faces.component.UIComponentBase.encodeEnd(UIComponentBase.java:875)
at com.sun.faces.renderkit.html_basic.HtmlBasicRenderer.encodeRecursive(HtmlBasicRenderer.java:312)
at com.sun.faces.renderkit.html_basic.GridRenderer.renderRow(GridRenderer.java:185)
at com.sun.faces.renderkit.html_basic.GridRenderer.encodeChildren(GridRenderer.java:129)
at javax.faces.component.UIComponentBase.encodeChildren(UIComponentBase.java:845)
at javax.faces.component.UIComponent.encodeAll(UIComponent.java:1779)
at javax.faces.component.UIComponent.encodeAll(UIComponent.java:1782)
at org.primefaces.component.accordionpanel.AccordionPanelRenderer.encodeTab(AccordionPanelRenderer.java:218)
at org.primefaces.component.accordionpanel.AccordionPanelRenderer.encodeTabs(AccordionPanelRenderer.java:147)
at org.primefaces.component.accordionpanel.AccordionPanelRenderer.encodeMarkup(AccordionPanelRenderer.java:91)
at org.primefaces.component.accordionpanel.AccordionPanelRenderer.encodeEnd(AccordionPanelRenderer.java:71)
at javax.faces.component.UIComponentBase.encodeEnd(UIComponentBase.java:875)
at javax.faces.component.UIComponent.encodeAll(UIComponent.java:1786)
at javax.faces.render.Renderer.encodeChildren(Renderer.java:168)
at javax.faces.component.UIComponentBase.encodeChildren(UIComponentBase.java:845)
at javax.faces.component.UIComponent.encodeAll(UIComponent.java:1779)
at javax.faces.component.UIComponent.encodeAll(UIComponent.java:1782)
at javax.faces.component.UIComponent.encodeAll(UIComponent.java:1782)
at com.sun.faces.application.view.FaceletViewHandlingStrategy.renderView(FaceletViewHandlingStrategy.java:402)
at com.sun.faces.application.view.MultiViewHandler.renderView(MultiViewHandler.java:128)
at com.sun.faces.lifecycle.RenderResponsePhase.execute(RenderResponsePhase.java:121)
at com.sun.faces.lifecycle.Phase.doPhase(Phase.java:101)
at com.sun.faces.lifecycle.LifecycleImpl.render(LifecycleImpl.java:139)
at javax.faces.webapp.FacesServlet.service(FacesServlet.java:594)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:305)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:368)
at org.springframework.security.web.access.intercept.FilterSecurityInterceptor.invoke(FilterSecurityInterceptor.java:109)
at org.springframework.security.web.access.intercept.FilterSecurityInterceptor.doFilter(FilterSecurityInterceptor.java:84)
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:380)
at org.springframework.security.web.access.ExceptionTranslationFilter.doFilter(ExceptionTranslationFilter.java:97)
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:380)
at org.springframework.security.web.session.SessionManagementFilter.doFilter(SessionManagementFilter.java:101)
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:380)
at org.springframework.security.web.authentication.AnonymousAuthenticationFilter.doFilter(AnonymousAuthenticationFilter.java:79)
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:380)
at org.springframework.security.web.authentication.rememberme.RememberMeAuthenticationFilter.doFilter(RememberMeAuthenticationFilter.java:119)
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:380)
at org.springframework.security.web.servletapi.SecurityContextHolderAwareRequestFilter.doFilter(SecurityContextHolderAwareRequestFilter.java:55)
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:380)
at org.springframework.security.web.savedrequest.RequestCacheAwareFilter.doFilter(RequestCacheAwareFilter.java:36)
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:380)
at org.springframework.security.web.authentication.www.BasicAuthenticationFilter.doFilter(BasicAuthenticationFilter.java:178)
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:380)
at org.springframework.security.web.authentication.AbstractAuthenticationProcessingFilter.doFilter(AbstractAuthenticationProcessingFilter.java:189)
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:380)
at org.springframework.security.web.authentication.logout.LogoutFilter.doFilter(LogoutFilter.java:106)
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:380)
at org.springframework.security.web.context.SecurityContextPersistenceFilter.doFilter(SecurityContextPersistenceFilter.java:79)
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:380)
at org.springframework.security.web.FilterChainProxy.doFilter(FilterChainProxy.java:170)
at org.springframework.web.filter.DelegatingFilterProxy.invokeDelegate(DelegatingFilterProxy.java:238)
at org.springframework.web.filter.DelegatingFilterProxy.doFilter(DelegatingFilterProxy.java:168)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:243)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:225)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:170)
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:473)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:168)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:100)
at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:928)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:120)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:407)
at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:999)
at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:565)
at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:309)
at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:909)
at java.lang.Thread.run(Thread.java:662)
错误发生在这个地方：
部门离职=（部门）价值;
拜托，我无法解决这个错误。请任何帮助!!
答案 0 :(得分：3)
我认为问题是noSelectionOption。
您应该从此选项中删除itemValue属性：
<f:selectItem itemLabel="Select one"
noSelectionOption="true"/>
或处理转换器中的itemValue=""个案。
答案 1 :(得分：3)
如果所有实体都使用getId（）方法实现接口，那么这是一个可以使用的通用GetAsString（如果所有实体都有一个Id作为主键，那么坦率地说这是个好主意）
@Override
public String getAsString(FacesContext facesContext, UIComponent component, Object object) {
if (object == null) {
return null;
}
if (object instanceof AbstractEntity) {
AbstractEntity e = (AbstractEntity) object;
return "" + e.getId();
}
else
throw new IllegalArgumentException("object " + object + " is of type " + object.getClass().getName() + "; expected AbstractEntity";
}